ubuntu-bug is the best way to file bugs. If you just run that command, it allows you to choose from various options what the issue you're getting might relate to. Otherwise, you can specify the name of a package as you run ubuntu-bug (like Dmitrijs pointed out).

The reason we say it's best, and why there's a redirect on the Report a Bug link, is that this makes sure there is more information on the bug which developers are likely to ask for anyway. So in this case, already having this included in the bug report hopefully avoids you getting asked to give more information, and tends to make the time from bug reporting to bug being fixed shorter.